The church was built and it effectively served its mission of converting hundreds of thousands of Indians to Catholicism. The story is fascinating because much of the success of Guadalupe lay in the symbols present in the image. While she is a typical Virgin image in most ways, to the Indians the sun, behind her, and the black moon, at her feet, represented the Aztec and Zapotec gods of the sun and moon, and Mary, herself, the mother earth they had always worshipped. It gave them a way to integrate their traditional religion into the new one.
Inside the Basilica we could stand on a conveyer that took us past the framed cloak of Juan Diego. Yes, this is the very poncho, still viable after more than 400 years. You see it from below on the conveyer, then you can go up one level to the church itself and see that it is actually on the wall behind the alter.
At the end of our tour we were taken to a gift shop where you could purchase anything and everything Guadalupe!
I have given you the very brief version of the story. There is much more information at this web site for anyone who is interested. (The magnifed images that show human figures in the Virgin's eyes are pretty interesting.) I am not Catholic, but I was glad we had visited the Basilica and heard the story and seen the image. What an insight into Mexican history and culture.